The rise of cardiovascular disease, type 2 diabetes mellitus, and other metabolic disorders in association with obesity is alarming. Unravelling the etiological factors of obesity is critical to developing novel therapies and interventions. Previou work has hypothesized that the origins of these metabolic diseases lies within exposure to adverse conditions during gestation. In fact, using a non-human primate model, it has previously been found that a maternal high fat diet induces non-alcoholic fatty liver disease (NAFLD), behavioral changes, and epigenetic alterations. Further, the juvenile microbiome is persistently altered after exposure to a maternal high fat diet in this model system. The microbiome is the collective genetic material of microbes living on and within the human body and has been implicated as a cause for obesity. However, immune responses of obese individuals appear to be altered, and inflammation is increased in fatty tissue, which may also alter the constituents of the microbiome. In this study, we propose to examine the interactions between the microbiome, the immune system, and fetal programming. The first aim will examine epigenetic regulation of inflammatory cytokines that are prevalent in obese individuals. Using a non-human primate model, regulation of inflammatory cytokine expression in association with maternal diet will be investigated in the intestine (colon) of both fetal and juvenile offspring by quantitative real-tim PCR (qPCR). Next, western blotting and mass spectrometry will assess alterations in histone modifications. Finally, gene expression and epigenetic regulation will be directly examined using chromatin immunoprecipation of key transcription factors and histone modifications followed by qPCR. This will determine the accessibility of the promoter and enhancer regions of these inflammatory cytokines. The second aim will investigate the role of the maternal diet in the localization and infiltration of immune cells into intestinal tissue. First, histology will be usedto determine if maternal diet is associated with immune cell infiltration into the tissue and when (in utero or postnatally) this infiltration occurs. Next, immunofluorescence will be utilized to determine if macrophages and/or T cells are infiltrating intestinal tissue upon exposure to a maternal high fat diet. The third aim will assess if maternal diet influences the developing microbiome independent of habitus. To distinguish between maternal diet versus maternal habitus, obese dams consuming a high fat diet for five years are switched to a control diet. The microbiome of the fetal and juvenile intestine will be examined via 16S rRNA sequencing. In this method, the V3V5 region of bacterial 16S rDNA will be amplified prior to 454 pyrosequencing. This method will also be utilized in the first and second aims to correlate the microbiome with epigenetic regulation and the immune system. Altogether, this proposal provides the knowledge base to facilitate the development of novel dietary interventions in pregnancy that will ameliorate metabolic diseases later in life.